Josh - The general name for this type of thing is leather carving or tooling. There are a lot of videos on you tube, but probably the best way to get started is to just dive in and fool around to see what the different tools can do. I've only been doing this for about 2 months and am still learning with every piece I do.
You can buy different leather carving kits from Tandy from beginner to advanced. That's a good place to start. I got the deluxe kit on sale for around $60 (regular price was around $250). The kit has all the basic tools you'll need, different stains, and several projects to practice on. Tandy has some really good sales, you just have to watch for them. Also, a member card will save you big $. I've seen the stamping tools as cheap as $4 each on sale (with a membership). It would be hard find them cheaper than that, even used. I'm not try to push Tandy down your throat, just telling you how I got started. There may be better sources, I just don't know of any. Some people make their own punches using large nails or bolts, but it would be very hard to make some of the tools with different textures on them.
I'm still pretty much a novice myself, but I'll answer any specific questions that I can if you need help. I'm not sure if you were following my earlier posts, but you can find a bit more info there regarding some of the techniques I used and the different tools. Check these out:
http://www.primitivearcher.com/smf/index.php/topic,23397.0.htmlhttp://www.primitivearcher.com/smf/index.php/topic,24297.45.html